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Refrigerator trouble


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The Dometic rm2652 will NOT cool on propane, and gets too cold on AC (below 30 degrees F). I have replaced the temp sensor running into the refrigerator, replaced the propane regulator (the flame looks fine), cleaned the burner orifice. The boiler on the cooling unit gets warm on gas, seems as hot as when it's on AC, but no cold in the fridge.

I suspect I need to replace the cooling unit, any thoughts?

 

Signed,

Warm Beer

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Your cooling unit must be working if it gets it down to 30 degrees. Must be something else --- control board maybe? Just did a quick google search and found a troubleshooting manual for Dometic -- works on electric but not gas - it said -- check your DC power supply. Controls need DC power.//// http://www.nationalserroscotty.org/resources/dometic-service-manual.pdf Here's the link for you.

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It's likely not the control board as it would act the same on AC -or- LP. The same with the thermostat and cooling unit.

 

My first question would be.. are you noticing this behavior when on shore power and switching between AC and LP, or only when LP is off shore power and on battery? If it is the second then there is more than likely a 12v DC supply issue (battery bank). You might have enough juice to run the control board so that the LP is igniting and heating, but not enough juice to run the cooling fan at sufficient speed.

 

If you're on shore power and cooling with LP and this is happening.. I have no clue unless you have a low pressure issue in your LP lines. However, you said the cooling unit feels just as hot on either AC or LP. Did you check all the way along the cooling coils or just in one spot? At the burner it might feel the same, but may not be pushing enough heat along the entire coil.

 

Just a thought.

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Check lp pressure at the gas valve. It must be at least 10.5". More like 11.5" would be better.

This is in inches of water collom. Not psi

You need to use a manometer to check the gas pressures

Also make sure the slots in the tube where the gas comes out to burn is clean and true to size. And that there is no dirt/rust blocking the tube from the gas oriface to the end of the tube.

While tou have the burner tube out tap on the boiler tube gently to loosen any rust that may be loose inside the tube while the burner tube is out of the way.

Also check that there is no blockage at the vent of the burner tube . Which you need to look down from the roof to see or remove the upper access panel if it is a slide

 

Yes a small amount of pressure,blockage can cause your symptoms

 

 

 

Safe Travels. Vern

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I had a very similar issue with my Norcold a couple of years ago. The unit would work fine on AC power, but wouldn't work on LP. I checked the burner and LP supply, etc, but everything seemed fine. It turned out a piece of expandable foam insulation had come loose and fallen into the burner exhaust tube/flue and got lodged just above the burner out of sight. I didn't find it until I physically started dismantling things. This impingement in the flue would not allow the burner to heat properly and prevented the absorption process from working on gas. As soon as I removed the blockage and put everything back together all was well. As Vern says above, a small amount of blockage can cause your symptoms.

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As far as Yaromes theories (possible low battery voltage when not plugged to shore power) I CAN CONCUR because when I had a similar problem and had the tech on the phone he wanted to know the exact DC voltage input (NOT just a trouble light) and warned me it didn't take but a few tenths of a volt low to make it inoperative!!!

 

As far as an insufficient flame, its hard to tell you by looking what it needs to be, but I have used my compressed air gun and teeny brushes and those fine acetylene torch tip cleaners etc etc to clean and blow the orfices and burner which improved the flame and made them work again on LP gas.

 

Check voltages when plugged versus unplugged,,,,,,,,,,,clean and blow and brush burner again (even though you did that already)

 

If all else fails, read the directions lol

 

John T

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The first thing that I'd suggest is to visit the website of Bryant RV and get the service manual for the Dometic 2652 specific model troubleshooting.

Looking to the troubleshooting guide, it states:

 

SYMPTOM
Insufficient cooling on Gas - cools properly on AC mode.

CAUSE
LP Gas Orifice

Flue Baffle

Flue Tube

Burner

Lower Circuit Board

 

Since the same cooling unit is used for both modes of cooling, I'd highly doubt that you need to replace yours but since it does include the flue area that is most suspect, that might correct at least some of the problem. The issue of cooling too much on 120V-ac and not cooling on propane seems like two different problems. Based upon my years of service tech career, I'd start by trouble shooting the lack of cooling on propane first, then once you find that problem check both modes again.

 

Have you been keeping it set to automatic, or did you manually select propane and/or electric? My thought process is much like that of Vern (who is a working RV tech) in the approach to the propane supply, but I would also check the flue tube and baffle as the service guide suggests.

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Yo Kirk, I have to agree with your statement based on my experience:

 

"My thought process is much like that of Vern (who is a working RV tech) in the approach to the propane supply, but I would also check the flue tube and baffle as the service guide suggests."

 

I say that because I've seen them where the flame looks fine to the untrained eye, BUT after a good cleaning and blowing out the cobwebs and especially soot and carbon THEY STARTED COOLING BETTER even though just by looking the flame didn't appear much different ???? I don't think it takes too much of a drop in heat energy for them to fail. Every few months I clean mine out and so far no trouble. My favorite after market fridge doo dad is the small interior fan that blows on the fins which prevents icing so the little woman doesn't have to defrost, Happy Wife Happy Life as they say.............I also added the small exterior muffin fan that helps with air flow and heat removal but cant honestly say I can see any difference.

 

John T Keep your cool now

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I say that because I've seen them where the flame looks fine to the untrained eye, BUT after a good cleaning and blowing out the cobwebs and especially soot and carbon THEY STARTED COOLING BETTER even though just by looking the flame didn't appear much different ???? I don't think it takes too much of a drop in heat energy for them to fail. Every few months I clean mine out and so far no trouble. My favorite after market fridge doo dad is the small interior fan that blows on the fins which prevents icing so the little woman doesn't have to defrost, Happy Wife Happy Life as they say.............I also added the small exterior muffin fan that helps with air flow and heat removal but cant honestly say I can see any difference.

What you are saying is exactly the problem the guide references as rust and dirt in the flue and on the flue baffle can inhibit the needed air movement through the unit and it effects the propane side more than the 120V side. Since you need to have both a proper gas flame and proper air movement through the flue in order to get the proper amount of cooling, it requires that both be good.

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  • 2 weeks later...

Thanks all for the help. It does seem that the flue is about 10 degrees warmer on AC....119F vs. 109F. The blue and the absorber temperature are very close to the same temperature on AC, but the absorber is barely warm on LP. I have blown the flue tube out, seems clean. I do not have a manometer, although I did install a new regulator last year and that didn't change anything (although I do not know that I am getting proper pressure at the unit!).

I appreciate all the suggestions and will keep plugging away...unfortunately I don't know of a repair place that would be any more competent than I am...and that is not much! I can change parts myself which is what most of the local shops would do, AFTER they charge for a diagnosis that is likely wrong.

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Dometic AES service manual: http://bryantrv.com/docs2/docs/AES.pdf

As far as Yaromes theories (possible low battery voltage when not plugged to shore power) I CAN CONCUR because when I had a similar problem and had the tech on the phone he wanted to know the exact DC voltage input (NOT just a trouble light) and warned me it didn't take but a few tenths of a volt low to make it inoperative!!!

 

As far as an insufficient flame, its hard to tell you by looking what it needs to be, but I have used my compressed air gun and teeny brushes and those fine acetylene torch tip cleaners etc etc to clean and blow the orfices and burner which improved the flame and made them work again on LP gas.

 

Check voltages when plugged versus unplugged,,,,,,,,,,,clean and blow and brush burner again (even though you did that already)

 

If all else fails, read the directions lol

 

John T

The minimum DC voltage to enable a Dometic frig to operate on LP is 9.6VDC, maximum is 22VDC: see pages 10 & 17 of http://www.nancyemmert.com/region6/Resources/NewDometicRefrigeratorManual.pdf

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